Up and Running Example

I'm trying to learn EXTjs 5.0 using the material in the up and running documentation. (http://ift.tt/1tvzM4z). However in the data package section, the example for associations doesn't appear to work. I've literally cut and pasted the different parts of the example and it almost works, but the it's not associating any of the posts with the user. Other than that, everything is working.

Before I knock myself out trying to figure out what's going wrong I'd thought I'd check and make sure there isn't a known problem with either the example or with 5.0 itself. I had to make one change already, quoting 'ajax' as a property value so the example isn't perfect and I want to make sure I'm not trying to solve an unsolvable problem.

Up and Running Example